Sensor system
AssigneeShiley Incorporated
InventorsMatthew J. Leader, Tadao Kamiya
Life of this patent
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Abstract
A sensor system for determining the pH or carbon dioxide concentration of a liquid medium comprising, in combination, a pH-insensitive fluorescent indicator and a PH-sensitive fluorescent indicator which act in concert or a single fluorescence indicator which emits fluorescent signals of different wavelengths in different carriers, which system(s) produce diverging signals, the ratio of which provides an accurate and stable determination of the parameter being measured. A method for determining pH and CO.sub.2 concentration is also disclosed.
Claims15
A sensor system for determining the pH of a liquid medium which comprises, in combination, a first fluorescent indicator whose fluorescence emission is insensitive to pH and a second fluorescent indicator whose fluorescence emission is highly sensitive to solution pH, which indicator combination is adapted to respond when a source of excitation radiation of wavelength .lambda..sub.o is applied to the system such that said first fluorescent indicator is selectively excited by said excitation radiation to emit pH-insensitive fluorescence emission at wavelength .lambda..sub.1, which emission overlaps the excitation radiation spectrum of said second fluorescent indicator, and said second indicator being excited by said emission radiation of wavelength .lambda..sub.1 and in turn emitting a pH-dependent fluorescence emission of wavelength .lambda..sub.2, the ratio of intensities of the radiation of wavelengths .lambda..sub.1/ .lambda..sub.2 providing a highly accurate, stable determination of the pH of said liquid medium.
A method for determining the pH of a liquid medium which comprises contacting said medium with a sensor system comprising, in combination, a first fluorescent indicator whose fluorescence emission is insensitive to pH and a second fluorescent indicator whose fluorescence emission is highly sensitive to solution pH, subjecting said sensor system to excitation radiation of a predetermined wavelength .lambda..sub.o, thereby selectively exciting said first fluorescent indicator to emit a pH-insensitive fluorescence emission at a wavelength of .lambda..sub.1, which emission overlaps the excitation radiation spectrum of said second fluorescent indicator and thus excites said second indicator to emit a pH-dependent fluorescence emission of wavelength .lambda..sub.2, and measuring either (i) the ratio of intensities of the emitted radiation of wavelengths .lambda..sub.1/ .lambda..sub.2, or (ii) the ratio derived from the intensity of the emitted radiation of wavelength .lambda..sub.1 and the intensity at the isobestic point between the emission curves of said first and second indications, thereby obtaining a highly accurate, stable determination of the pH of said liquid medium.
A sensor system for the determination of the concentration of carbon dioxide in a liquid medium which comprises, in combination, a first fluorescent indicator whose fluorescence emission is insensitive to pH and a second fluorescent indicator whose fluorescent emission is highly sensitive to solution pH, which indicator combination is associated with a bicarbonate solution bounded by a carbon dioxide-permeable membrane, and is adapted to respond when a source of excitation radiation of wavelength .lambda..sub.o is applied to the system such that said first fluorescent indicator is selectively excited by said excitation radiation to emit a pH-insensitive fluorescence emission at wavelength .lambda..sub.1, which emission overlaps the excitation radiation spectrum of said second fluorescent indicator, said second indicator being excited by said emission radiation of wavelength .lambda..sub.1, and in turn emitting a pH-dependent fluorescence emission of wavelength .lambda..sub.2, the ratio of intensities of the radiation of wavelengths .lambda..sub.1 /.lambda..sub.2 providing an indication of the solution pH within the membrane and thereby a highly accurate, stable determination of the concentration of carbon dioxide in the liquid medium.
A method for determining the concentration of carbon dioxide in a liquid medium which comprises contacting said medium with a sensor system comprising, in combination, a first fluorescent indicator whose fluorescence emission is insensitive to pH and a second fluorescent indicator whose fluorescence emission is highly sensitive to solution pH, which indicators are associated with a bicarbonate solution bounded by a carbon dioxide-permeable membrane, subjecting said sensor system to excitation radiation of a predetermined wavelength .lambda..sub.o, thereby selectively exciting said first fluorescent indicator to emit a pH-insensitive fluorescence emission at a wavelength of .lambda..sub.1, which emission overlaps the excitation radiation spectrum of said second fluorescent indicator and thus excites said second indicator to emit a pH-dependent fluorescent emission of wavelength .lambda..sub.2, and measuring either (i) the ratio of intensities of the emitted radiation of wavelengths .lambda..sub.1 /.lambda..sub.2, or (ii) the ratio derived from the intensity of the emitted radiation of wavelength .lambda..sub.1 and the intensity at the isobestic point between the emission curves of said first and second indications, thereby obtaining an indication of the solution pH within the membrane and thus a highly accurate, stable determination of the concentration of carbon dioxide in the liquid medium.
Dependencies are inferred from the claim text.